xref: /kvm-unit-tests/powerpc/tm.c (revision 851ef5165069857e56e35b01c8ed43b115c2737e)
1 /*
2  * Transactional Memory Unit Tests
3  *
4  * Copyright 2016 Suraj Jitindar Singh, IBM.
5  *
6  * This work is licensed under the terms of the GNU LGPL, version 2.
7  */
8 #include <libcflat.h>
9 #include <asm/hcall.h>
10 #include <asm/processor.h>
11 #include <asm/time.h>
12 #include <asm/handlers.h>
13 #include <asm/smp.h>
14 #include <asm/setup.h>
15 #include <devicetree.h>
16 
17 /* Check "ibm,pa-features" property of a CPU node for the TM flag */
cpu_has_tm(int fdtnode,u64 regval __unused,void * ptr)18 static void cpu_has_tm(int fdtnode, u64 regval __unused, void *ptr)
19 {
20 	const struct fdt_property *prop;
21 	int plen;
22 
23 	prop = fdt_get_property(dt_fdt(), fdtnode, "ibm,pa-features", &plen);
24 	if (!prop)	/* No features means TM is also not available */
25 		return;
26 	/* Sanity check for the property layout (first two bytes are header) */
27 	assert(plen >= 8 && prop->data[1] == 0 && prop->data[0] <= plen - 2);
28 
29 	/*
30 	 * The "Transactional Memory Category Support" flags are at byte
31 	 * offset 22 and 23 of the attribute type 0, so when adding the
32 	 * two bytes for the header, we've got to look at offset 24 for
33 	 * the TM support bit.
34 	 */
35 	if (prop->data[0] >= 24 && (prop->data[24] & 0x80) != 0)
36 		*(int *)ptr += 1;
37 }
38 
39 /* Check amount of CPUs nodes that have the TM flag */
count_cpus_with_tm(void)40 static int count_cpus_with_tm(void)
41 {
42 	int ret;
43 	int available = 0;
44 
45 	ret = dt_for_each_cpu_node(cpu_has_tm, &available);
46 	if (ret < 0)
47 		return ret;
48 
49 	return available;
50 }
51 
52 /*
53  * Enable transactional memory
54  * Returns:	FALSE - Failure
55  *		TRUE - Success
56  */
enable_tm(void)57 static bool enable_tm(void)
58 {
59 	uint64_t msr = 0;
60 
61 	asm volatile ("mfmsr %[msr]" : [msr] "=r" (msr));
62 
63 	msr |= (((uint64_t) 1) << 32);
64 
65 	asm volatile ("mtmsrd %[msr]\n\t"
66 		      "mfmsr %[msr]" : [msr] "+r" (msr));
67 
68 	return !!(msr & (((uint64_t) 1) << 32));
69 }
70 
71 /*
72  * Test H_CEDE call while transactional memory transaction is suspended
73  *
74  * WARNING: This tests for a known vulnerability in which the host may go down.
75  * Probably best not to run this if your host going down is going to cause
76  * problems.
77  *
78  * If the test passes then your kernel probably has the necessary patch.
79  * If the test fails then the H_CEDE call was unsuccessful and the
80  * vulnerability wasn't tested.
81  * If the test hits the vulnerability then it will never complete or report and
82  * the qemu process will block indefinitely. RCU stalls will be detected on the
83  * cpu and any process scheduled on the lost cpu will also block indefinitely.
84  */
test_h_cede_tm(int argc,char ** argv)85 static void test_h_cede_tm(int argc, char **argv)
86 {
87 	int i;
88 
89 	if (argc > 2)
90 		report_abort("Unsupported argument: '%s'", argv[2]);
91 
92 	if (!start_all_cpus(halt))
93 		report_abort("Failed to start secondary cpus");
94 
95 	if (!enable_tm())
96 		report_abort("Failed to enable tm");
97 
98 	/*
99 	 * Begin a transaction and guarantee we are in the suspend state
100 	 * before continuing
101 	 */
102 	asm volatile ("1: .long 0x7c00051d\n\t"	/* tbegin. */
103 		      "beq 2f\n\t"
104 		      ".long 0x7c0005dd\n\t"	/* tsuspend. */
105 		      "2: .long 0x7c00059c\n\t"	/* tcheck cr0 */
106 		      "bf 2,1b" : : : "cr0");
107 
108 	for (i = 0; i < 500; i++) {
109 		msleep(10);
110 		mdelay(5);
111 	}
112 
113 	report(i == 500, "H_CEDE TM");
114 }
115 
116 struct {
117 	const char *name;
118 	void (*func)(int argc, char **argv);
119 } hctests[] = {
120 	{ "h_cede_tm", test_h_cede_tm },
121 	{ NULL, NULL }
122 };
123 
main(int argc,char ** argv)124 int main(int argc, char **argv)
125 {
126 	bool all;
127 	int i, cpus_with_tm;
128 
129 	report_prefix_push("tm");
130 
131 	cpus_with_tm = count_cpus_with_tm();
132 	if (cpus_with_tm == 0) {
133 		report_skip("TM is not available");
134 		goto done;
135 	}
136 	/* kvm-unit-tests can limit number of CPUs present */
137 	/* KVM does not report TM in secondary threads in POWER9 */
138 	report_kfail(host_is_kvm, cpus_with_tm >= nr_cpus_present,
139 	       "TM available in all 'ibm,pa-features' properties");
140 
141 	all = argc == 1 || !strcmp(argv[1], "all");
142 
143 	for (i = 0; hctests[i].name != NULL; i++) {
144 		if (all || strcmp(argv[1], hctests[i].name) == 0) {
145 			report_prefix_push(hctests[i].name);
146 			hctests[i].func(argc, argv);
147 			report_prefix_pop();
148 		}
149 	}
150 
151 done:
152 	report_prefix_pop();
153 	return report_summary();
154 }
155